A high thermal conductivity and high emissivity protective coating and preparation method thereof

Abstract

The present invention discloses a high-thermal-conductivity and high-emissivity protective coating, which relates to the technical field of high-temperature protective coatings. The coating comprises a silicon-based bonding layer, a high-conductivity heat transfer layer, and a high-emissivity heat dissipation layer, which are sequentially prepared on a carbon fiber-reinforced ceramic-based composite material substrate to form a high-thermal-conductivity and high-emissivity protective coating. The protective coating prepared by the present invention has excellent bonding strength, phase structure stability, and chemical compatibility. Compared with ordinary high-temperature protective coatings, the present coating has higher thermal conductivity and emissivity. During high-temperature service, the heat from the tip hotspot area can be quickly transferred to the high-conductivity fiber to release the accumulated stress. The higher emissivity further transfers the redundant heat on the coating surface to the service environment in the form of electromagnetic waves, significantly increasing the operating temperature of the composite material in an oxidizing environment and extending the service life of the leading edge components of the aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature protective coatings, and in particular to a high-thermal-conductivity and high-emissivity protective coating and a preparation method thereof. Background Art

[0002] Hypersonic vehicles are a key pillar of the development of rapid strike systems. High-temperature protection, coupled with the complex corrosive effects of their service environments, has always been a core technology in the development of hypersonic vehicles and other types of aircraft. For vehicles undergoing high-Mach number re-entry or prolonged atmospheric cruising, structural thermal protection and its impact on aerodynamic performance remain crucial. The nose, as the head of a blunt-bodied vehicle, experiences the harshest aerodynamic heating environment and is therefore a key area for thermal protection.

[0003] High thermal conductivity carbon fiber reinforced high temperature composite materials include C f / ZrC、C f / TaC、C f / HfC, etc., have the advantages of thermal shock resistance, creep resistance, ablation resistance, wear resistance, etc. At the same time, its extremely high high-temperature thermal conductivity can quickly transfer heat from the high-temperature area of ​​the leading edge to the low-temperature area, and has the characteristics of high modulus, high strength and high toughness. It has been widely used in the aerospace field. These components generally work in harsh environments with high temperature and oxygen, and have higher requirements for anti-oxidation and anti-erosion performance than rocket engines. As for high-temperature composite materials themselves, their many excellent properties can only be exerted under the protection of an inert atmosphere. Since carbon fiber begins to oxidize at about 400°C in the air, the oxidation process starts with the flow of oxygen in the gas medium to the material boundary, and the adsorption surface diffuses to the north, and a carbon oxidation reaction occurs under the catalysis of impurity particles (Na, S, K, Mg), thereby causing the weight loss failure of the composite material, which is difficult to meet the use requirements under high temperature. Studies have shown that the use of high-temperature protective coatings is the most effective means to solve problems such as insufficient high-temperature oxidation resistance and thermal stress concentration of such composite materials. However, traditional thermal protective coatings have low thermal conductivity and emissivity, making it difficult to quickly transfer the redundant heat generated by aerodynamic friction with high-speed airflow during component service to the underlying high-conductivity ceramic substrate, thereby alleviating heat concentration in the surface working area. Therefore, there is an urgent need to develop high-temperature protective coatings with excellent thermal conductivity and heat dissipation properties for the surface of high-thermal conductivity carbon fiber reinforced high-temperature composites. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high thermal conductivity and high emissivity protective coating and its preparation method, aiming to meet the service requirements of the coating while solving problems such as mismatch in thermal expansion coefficients between coatings, low internal stress tolerance, heat conduction speed and slow heat dissipation rate on the coating surface.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A high thermal conductivity and high emissivity protective coating comprises a carbon fiber reinforced ceramic matrix composite material substrate, on which a silicon-based bonding layer, a high thermal conductivity layer and a high emissivity heat dissipation layer are sequentially prepared to form the high thermal conductivity and high emissivity protective coating.

[0007] Preferably, the silicon-based bonding layer is composed of dispersed Al2O3 doped phase optimized Si ceramic material; the high thermal conductivity layer is composed of BN-RE x Al 1-x The high-radiative heat dissipation layer is composed of TaO4 ceramic material, the RE is one of Y, Yb, Sm, Eu, Ho or Lu, and the value of x is in the range of 0.02-0.1; the high-radiative heat dissipation layer is composed of Pt-A ​​metal, A is one or two of the refractory metals Ir, Rh, Mo or Co, and the one or two of the refractory metals Ir, Rh, Mo or Co are optimized with a platinum black layer to form a high-radiative heat dissipation layer.

[0008] Preferably, the thickness of the silicon-based bonding layer is 50-80 μm, the thickness of the high thermal conductivity layer is 100-150 μm, the thickness of the high emissivity heat dissipation layer is 5-10 μm, and the total thickness of the high thermal conductivity and high emissivity protective coating system is 155-240 μm.

[0009] The silicon-based adhesive layer preferably has a density of 96-99%, resulting in a compact coating structure and uniform component distribution, providing ample silicon sources for the coating system. The high-conductivity thermal conductivity layer has a density range of 90-95%, maintaining high thermal conductivity while improving the coating's stress tolerance through structural design.

[0010] Due to the adoption of the above technical solution, a silicon-based bonding layer is prepared on the surface of a high-thermal-conductivity carbon fiber reinforced high-temperature composite material. The bonding layer material is composed of an SI ceramic material with a dispersed Al2O3 doped phase optimized. The coating material can uniformly generate mullite components within the system in a high-temperature aerobic service environment, thereby increasing the fracture toughness of the coating, improving corrosion resistance, maintaining physical and chemical properties similar to those of the substrate for a long time, and consolidating the bonding strength between the substrate and the outer protective layer. The ceramic high-conductivity heat transfer layer material is composed of a two-phase ceramic material of boron nitride and rare earth tantalate, wherein boron nitride as a thermally conductive particle is distributed around the rare earth tantalate skeleton structure to form a through-type thermal conductive chain, which greatly improves the thermal conductivity rate of the material. Rare earth tantalate as a supporting material has high thermal stability, oxidation resistance, corrosion resistance, and a thermal expansion coefficient adapted to the substrate, which can ensure the stability of the coating structure under service conditions in a wide temperature range. The metal high-radiation heat dissipation layer material is composed of a refractory metal optimized platinum black layer. The platinum black has a fine structure and high bonding strength. The material emissivity can reach 0.88-0.98. Through solid solution strengthening of refractory metals such as Ir, Rh, Mo and Co, its high-temperature stability and impact strength are further improved. The coating has a stable impact-resistant and corrosion-resistant surface layer while meeting the heat dissipation requirements, greatly improving the durability of the coating function and the service life of the composite material.

[0011] At the same time, according to the position of each functional layer in the coating system and the service performance requirements, coating materials and preparation processes with different excellent properties are selected respectively, so as to meet the service requirements of the coating while solving problems such as mismatch of thermal expansion coefficients between coatings, low internal stress tolerance, heat conduction speed and slow heat dissipation rate of the coating surface.

[0012] A method for preparing a high thermal conductivity and high emissivity protective coating comprises the following steps:

[0013] (1) Screening the spray powders of the silicon-based bonding layer and the high-conductivity heat transfer layer respectively to obtain the silicon-based bonding layer spray spherical powder and the high-conductivity heat transfer layer spray spherical powder with uniform fluidity and particle size distribution, and setting aside for use;

[0014] (2) pretreating the carbon fiber reinforced ceramic matrix composite material matrix to obtain a carbon fiber reinforced ceramic matrix composite material matrix having a rough and clean surface;

[0015] (3) preparing a silicon-based bonding layer on a rough and clean carbon fiber reinforced ceramic matrix composite substrate using a vacuum plasma spraying method;

[0016] (4) preparing a high-conductivity heat transfer layer on the surface of the silicon-based bonding layer by using a supersonic flame spraying method to obtain a spray coating system;

[0017] (5) heat-treating the spray coating system using a muffle furnace until stress inside the spray coating system is removed, thereby obtaining a stress-removed spray coating;

[0018] (6) A high-radiation heat dissipation layer is prepared on the surface of the spray coating by magnetron sputtering, that is, a high-thermal conductivity and high-radiation protective coating of a carbon fiber reinforced ceramic matrix composite material matrix is ​​obtained.

[0019] The silicon-based bonding layer uses Al2O3-Si two-phase spherical spray powder, and the high-conductivity heat transfer layer uses BN-RE x Al 1-X TaO4 two-phase spherical spray powder.

[0020] By adopting the above method, the superior performance and structural stability of the high thermal conductivity and high emissivity protective coating can be achieved.

[0021] Preferably, the flowability of the spherical powder sprayed on the silicon-based bonding layer in step (1) is 25-40 s / 50 g, and the particle size distribution is 25-50 μm; the flowability of the powder sprayed on the high-conductivity and heat-conductivity layer is 35-55 s / 50, and the particle size distribution is 37-80 μm. This allows for screening of the powders sprayed on the silicon-based bonding layer and the high-conductivity and heat-conductivity layer, ensuring uniform powder flowability and particle size distribution.

[0022] Preferably, the pretreatment in step (2) is to use sandpaper with increasing mesh size of 80-320 to polish the carbon fiber reinforced ceramic matrix composite material matrix in sequence, rinse the surface grinding residue with anhydrous ethanol, place it in a high temperature drying at 80-110 ° C for 30-90 minutes, and after drying, use 1-40 mesh gravel to sandblast the carbon fiber reinforced ceramic matrix composite material matrix, and blow it after the sandblasting is completed to obtain a carbon fiber reinforced ceramic matrix composite material matrix with a rough and clean surface. The gravel uses medium-coarse white corundum and brown corundum, with a mesh size range of 1-40 mesh, a sandblasting pressure of 0.6-0.75 MPa, a sandblasting distance of 100-150 mm, and a sandblasting angle of 50-70 ° C.

[0023] By adopting the above method, the surface pretreatment of the high-conductivity carbon fiber reinforced ceramic matrix composite material is achieved, ensuring the surface roughness and cleanliness.

[0024] Preferably, the parameters of the vacuum plasma spraying method in step (3) are: power supply power of 40-66kW, operating current of 500-600A, operating voltage of 80-110V, argon flow rate of 2000-2700L / h, hydrogen flow rate of 500-700L / h, four-way powder feeding rate of 200-350L / h, rotation speed of 0.7-1.5r / s, and cooling temperature of 50-70°C. In this way, the silicon-based bonding layer is prepared on the surface of the high-conductivity carbon fiber reinforced ceramic matrix composite material.

[0025] Preferably, the parameters of the supersonic flame spraying method in step (4) are: oxygen flow rate 1600-2100 SCFH, kerosene flow rate 6-8.5 gpm, powder feed rate 40-65 g / min, carrier gas flow rate 20-25 SCFH, spray distance 320-400 mm, step distance 4-7 mm, and line speed 300-450 mm / s. In this way, a high-conductivity heat transfer layer is prepared on the surface of the silicon-based adhesive layer.

[0026] Preferably, the heat treatment parameters in step (5) are: heat treatment at 900-1150°C for 1.5-3h, thereby achieving heat treatment of the sprayed sample in a muffle furnace and removing residual stress within the coating system. The magnetron sputtering parameters in step (6) are: vacuum degree 1.3-2.0 Pa, sputtering current 100-120 mA, sputtering time 20-40 min, correction factor 1.0-2.0, sample stage rotation speed 6-15 rpm, water inlet temperature 20-35°C, and return water temperature 50-70°C, thereby achieving the preparation of a high-radiative heat dissipation layer on the surface of the high-conductivity heat transfer layer.

[0027] According to the position of each functional layer in the coating system and the service performance requirements, coating materials and preparation processes with different excellent properties are selected respectively to meet the service requirements of the coating while solving problems such as mismatch of thermal expansion coefficients between coatings, low internal stress tolerance, heat conduction speed and slow heat dissipation rate of the coating surface.

[0028] The beneficial effects of the present invention are:

[0029] 1. The bonding layer material of the present invention is composed of an optimized SI ceramic material with a dispersed Al2O3 doping phase. This coating material can uniformly generate mullite components within the system in a high-temperature oxygen service environment, increasing the coating's fracture toughness and corrosion resistance, maintaining physical and chemical properties similar to those of the substrate over a long period of time, and strengthening the bond strength between the substrate and the outer protective layer. The ceramic high-conductivity heat transfer layer material is composed of a two-phase ceramic material of boron nitride and rare earth tantalate. Boron nitride, as thermally conductive particles, surrounds the rare earth tantalate skeleton structure, forming a through-type heat-conducting chain, significantly improving the material's thermal conductivity. The rare earth tantalate, as a supporting material, has high thermal stability, oxidation resistance, corrosion resistance, and a thermal expansion coefficient compatible with the substrate, ensuring the stability of the coating structure under wide temperature range service conditions. The metal high-radiation heat dissipation layer material is composed of a refractory metal optimized platinum black layer. The platinum black has a fine structure and high bonding strength. The material emissivity can reach 0.88-0.98. Through solid solution strengthening of refractory metals such as Ir, Rh, Mo and Co, its high-temperature stability and impact strength are further improved. The coating has a stable impact-resistant and corrosion-resistant surface layer while meeting the heat dissipation requirements, greatly improving the durability of the coating function and the service life of the composite material.

[0030] 2. After the sprayed coating of the present invention is purged and cooled, a special heat treatment process is added to recrystallize the metastable state of the coating material formed by rapid cooling through high-temperature aging. While restoring the physical phase of the powder material, it also eliminates the hidden dangers caused by volume phase change, thereby improving the stress tolerance of the coating.

[0031] 3. Based on the optimized intrinsic performance of different functional layer materials and the service environment conditions, the present invention uses different advantageous coating equipment to prepare functional layers of different thicknesses and porosities through coating structure design, thereby further optimizing coating performance and obtaining a high thermal conductivity and high emissivity protective coating. Compared with traditional high-temperature protective coatings, it can quickly transfer heat from the tip hotspot area to the high-conductivity fiber, releasing accumulated thermal stress. At the same time, the higher emissivity further transfers the redundant heat on the coating surface to the service environment in the form of electromagnetic waves, significantly increasing the operating temperature of the composite material in an oxidizing environment, thereby extending the service life of the leading edge components of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The actual pictures of the high thermal conductivity and high emissivity protective coating embodiment of the present invention and comparative example 4;

[0033] Figure 2 Schematic diagram of the high thermal conductivity and high emissivity protective coating system structure of the present invention;

[0034] Figure 3 This is the emissivity curve of the high thermal conductivity and high emissivity protective coating embodiment and the comparative example of the present invention;

[0035] Figure 4 These are the thermal conductivity curves of the high thermal conductivity and high emissivity protective coating embodiments and comparative examples of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] Example 1

[0039] A method for preparing a high thermal conductivity and high emissivity protective coating comprises the following steps:

[0040] (1) After spray granulation of Si powder, sprayable Si spherical powder is obtained. After mixing the sprayable Si spherical powder with sprayable Al2O3 powder, the powder is placed in an automatic vibrating sieving machine, the vibration frequency is set to 700r / min, the upper and lower limits of the Si-Al2O3 mixed powder sieve are changed to 300-500 mesh, and the sieved Si-Al2O3 mixed powder is obtained. 50g of the sieved Si-Al2O3 mixed powder is weighed and placed in a calibrated Hall flow tester. The powder passing time is recorded. The fluidity of the sieved Si-Al2O3 mixed powder is 25s / 50g. The Si-Al2O3 mixed powder is collected and dried for storage; the upper and lower limits of the automatic vibrating sieving machine sieve are changed to 180-400 mesh, and BN-Y 0.02 Al 0.98 The TaO4 two-phase powder is placed in an automatic vibrating sieving machine to obtain the sieved BN-Y 0.02 Al 0.98 TaO4 two-phase powder, weigh 50g of sieved BN-Y 0.02 Al 0.98 The TaO4 two-phase powder is placed in the calibrated Hall flow tester, and the time for the powder to pass through is recorded. 0.02 Al 0.98 The fluidity of TaO4 two-phase powder is 35s / 50g, and BN-Y 0.02 Al 0.98 The TaO4 two-phase powder is dried and stored for later use.

[0041] (2) Use 80-320 increasing grit sandpaper (80 grit, 120 grit, 240 grit, 320 grit) to vertically polish the carbon fiber reinforced ceramic matrix composite matrix material (C f / ZrC matrix material), after washing the surface grinding residue with anhydrous ethanol, put it in 80℃ high temperature drying for 30min, and further use 20 mesh medium coarse sand white corundum to C f The ZrC matrix material was sandblasted. The sandblasting parameters were set as follows: sandblasting pressure 0.6 MPa, sandblasting distance 100 mm, sandblasting angle 50 °, and the borax surface was cleaned with an air gun. f / ZrC matrix material should be stored dry.

[0042] (3) Vacuum atmospheric plasma spraying on C f Prepare Si-Al2O3 bonding layer on the surface of / ZrC matrix material, slowly pour Si-Al2O3 mixed spherical powder into four-way powder feeder, and fThe ZrC matrix material was installed on a plasma spraying tool. The vacuum atmospheric plasma spraying parameters were set as follows: power supply 40 kW, operating current 500 A, operating voltage 80 V, argon flow rate 2000 L / h, hydrogen flow rate 500 L / h, powder feeding rate 200 L / h, rotation speed 0.7 r / s, and cooling temperature 50°C; the coating thickness of the silicon-based bonding layer was 50 μm, and the density was 96%.

[0043] (4) Preparation of BN-Y on the surface of Si-Al2O3 bonding layer by supersonic flame spraying 0.02 Al 0.98 TaO4 ceramic high conductivity heat transfer layer, BN-Y 0.02 Al 0.98 TaO4 two-phase powder was slowly poured into the powder feeder, and the prepared bonding layer substrate was installed on the flame spraying tool. The supersonic flame spraying parameters were set as follows: barrel length 4 inches, oxygen flow rate 1600 SCFH, kerosene flow rate 6 gpm, powder feed rate 40 g / min, carrier gas flow rate 20 SCFH, spray distance 320 mm, step distance 4 mm, and linear speed 300 mm / s. BN-Y 0.02 Al 0.98 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 100 μm and the density is 90%.

[0044] (5) Waiting for C f / ZrC substrate surface Si-Al2O3 bonding layer, BN-Y 0.02 Al 0.98 After forming the TaO4 ceramic high-conductivity heat transfer layer, the spray coating system was placed in a muffle furnace for high-temperature heat treatment. The heat treatment parameters were set to a heat treatment temperature of 900°C and a heat treatment time of 1.5 hours, followed by cooling with the furnace.

[0045] (6) Magnetron sputtering on BN-Y 0.02 Al 0.98 A Pt-Ir high radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high heat conduction layer. The Pt-Ir target was fixed and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of the magnetron sputtering were: vacuum degree 1.3 Pa, sputtering current 100 mA, sputtering time 20 min, correction factor 1.0, sample stage rotation speed 6 rpm, water inlet temperature 20 ° C, return water temperature 50 ° C; the thickness of the Pt-Ir high radiation heat dissipation layer was 5 μm. The C f High thermal conductivity and high emissivity protective coating based on / ZrC matrix material.

[0046] The high thermal conductivity and high emissivity protective coating material prepared is as follows Figure 1 (Left) shown.

[0047] Schematic diagram of the cross section of the coating system Figure 2 shown.

[0048] Example 2

[0049] The difference between this embodiment and embodiment 1 is that:

[0050] Vacuum atmospheric plasma spraying on C f When preparing the Si-Al2O3 bonding layer on the surface of the ZrC substrate, vacuum atmospheric plasma spraying parameters were: power supply 46.2kW, operating current 550A, operating voltage 84V, argon flow rate 2100L / h, hydrogen flow rate 530L / h, powder feed rate 210L / h, rotation speed 0.9r / s, and cooling temperature 50°C. The coating thickness of the silicon-based bonding layer was 59μm, and the density was 98%.

[0051] BN-RE x Al 1-x The RE of TaO4 high conductivity heat transfer layer is Yb, and BN-Yb is obtained. 0.06 Al 0.94 TaO4 ceramic high conductivity heat transfer layer is prepared by supersonic flame spraying on the surface of Si-Al2O3 bonding layer. 0.06 Al 0.94 When spraying TaO4 ceramic high-conductivity heat transfer layer, the supersonic flame spraying parameters are set as follows: barrel length 4 inches, oxygen flow rate 1750 SCFH, kerosene flow rate 7.5 gpm, powder feed rate 51 g / min, carrier gas flow rate 23 SCFH, spray distance 330 mm, step distance 6 mm, and linear speed 400 mm / s. 0.06 Al 0.94 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 134 μm and the density is 91%.

[0052] The A in the Pt-A ​​metal high radiation heat dissipation layer is Rh, and a Pt-Rh high radiation heat dissipation layer is obtained. 0.06 Al 0.94 A Pt-Rh high radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high thermal conductivity layer. The Pt-Rh target was installed and fixed, and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of magnetron sputtering were as follows: vacuum degree 1.3 Pa, sputtering current 100 mA, sputtering time 23 min, correction factor 1.50, sample stage rotation speed 6 rpm, water inlet temperature 27 ° C, and return water temperature 50 ° C; the thickness of the Pt-Rh high radiation heat dissipation layer was 9 μm.

[0053] Example 3

[0054] The difference between this embodiment and embodiment 1 is that:

[0055] Vacuum atmospheric plasma spraying on C fWhen preparing the Si-Al2O3 bonding layer on the ZrC substrate, vacuum atmospheric plasma spraying parameters were: power supply 53.4 kW, operating current 600 A, operating voltage 89 V, argon flow rate 2300 L / h, hydrogen flow rate 550 L / h, powder feed rate 300 L / h, rotation speed 0.8 rpm, and cooling temperature 50°C. The resulting Si-based bonding layer had a coating thickness of 65 μm and a density of 98%.

[0056] BN-RE x Al 1-x The RE of TaO4 high conductivity heat transfer layer is Sm, and BN-Sm is obtained. 0.04 Al 0.96 TaO4 ceramic high conductivity heat transfer layer is prepared by supersonic flame spraying on the surface of Si-Al2O3 bonding layer. 0.04 Al 0.96 When spraying TaO4 ceramic high-conductivity heat transfer layer, the supersonic flame spraying parameters are set as follows: barrel length 4 inches, oxygen flow rate 1730 SCFH, kerosene flow rate 7.0 gpm, powder feed rate 57 g / min, carrier gas flow rate 25 SCFH, spray distance 320 mm, step distance 7 mm, and linear speed 450 mm / s. 0.04 Al 0.96 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 150μm and the density is 95%.

[0057] The A in the Pt-A ​​metal high radiation heat dissipation layer is Mo, and the Pt-Mo high radiation heat dissipation layer is obtained by magnetron sputtering on the BN-Sm 0.04 Al 0.96 A Pt-Mo high-radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high-conductivity heat transfer layer. The Pt-Mo target was installed and fixed, and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of magnetron sputtering were as follows: vacuum degree 1.7 Pa, sputtering current 100 mA, sputtering time 40 min, correction factor 1.50, sample stage rotation speed 6 rpm, water inlet temperature 30 ° C, and return water temperature 68 ° C; the thickness of the Pt-Rh high-radiation heat dissipation layer was 8 μm.

[0058] Example 4

[0059] The difference between this embodiment and embodiment 1 is that:

[0060] Vacuum atmospheric plasma spraying on C fWhen preparing the Si-Al2O3 bonding layer on the surface of the ZrC substrate, vacuum atmospheric plasma spraying parameters were: power supply 51.9 kW, operating current 570 A, operating voltage 91 V, argon flow rate 2600 L / h, hydrogen flow rate 650 L / h, powder feed rate 350 L / h, rotation speed 1.2 rpm, and cooling temperature 54°C. The resulting Si-based bonding layer had a coating thickness of 80 μm and a density of 96%.

[0061] BN-RE x Al 1-x The RE of TaO4 high conductivity heat transfer layer is Eu, and BN-Eu is obtained. 0.1 Al 0.90 TaO4 ceramic high conductivity heat transfer layer is prepared by supersonic flame spraying on the surface of Si-Al2O3 bonding layer. 0.1 Al 0.90 When spraying TaO4 ceramic high-conductivity heat transfer layer, the supersonic flame spraying parameters are set as follows: barrel length 4 inches, oxygen flow rate 1854 SCFH, kerosene flow rate 7.8 gpm, powder feed rate 42 g / min, carrier gas flow rate 21 SCFH, spray distance 380 mm, step distance 5 mm, and linear speed 410 mm / s. 0.1 Al 0.90 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 147 μm and the density is 94%.

[0062] The A in the Pt-A ​​metal high radiation heat dissipation layer is Co, and a Pt-Co high radiation heat dissipation layer is obtained. 0.1 Al 0.90 A Pt-Co high-radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high-conductivity heat transfer layer. The Pt-Co target was installed and fixed, and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of magnetron sputtering were as follows: vacuum degree 1.5 Pa, sputtering current 120 mA, sputtering time 37 min, correction factor 1.0, sample stage rotation speed 10 rpm, water inlet temperature 35 ° C, and return water temperature 70 ° C; the thickness of the Pt-Rh high-radiation heat dissipation layer was 10 μm.

[0063] Example 5

[0064] The difference between this embodiment and embodiment 1 is that:

[0065] Vacuum atmospheric plasma spraying on C fWhen preparing the Si-Al2O3 bonding layer on the surface of the ZrC substrate, vacuum atmospheric plasma spraying parameters were: power supply 59.2 kW, operating current 580 A, operating voltage 102 V, argon flow rate 2400 L / h, hydrogen flow rate 520 L / h, powder feed rate 250 L / h, rotation speed 1.4 rpm, and cooling temperature 60°C. The coating thickness of the Si-based bonding layer was 74 μm, with a density of 97%.

[0066] BN-RE x Al 1-x The RE of the TaO4 high-conductivity heat transfer layer is Ho, and BN-Ho is obtained. 0.08 Al 0.92 TaO4 ceramic high conductivity heat transfer layer is prepared by supersonic flame spraying on the surface of Si-Al2O3 bonding layer. 0.08 Al 0.92 When spraying TaO4 ceramic high-conductivity heat transfer layer, the supersonic flame spraying parameters are set as follows: barrel length 4 inches, oxygen flow rate 2100 SCFH, kerosene flow rate 8.5 gpm, powder feed rate 59 g / min, carrier gas flow rate 24 SCFH, spray distance 400 mm, step distance 6 mm, and linear speed 350 mm / s. 0.08 Al 0.92 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 110 μm and the density is 94%.

[0067] The A in the Pt-A ​​metal high radiation heat dissipation layer is Ir-Rh, and a Pt-Ir-Rh high radiation heat dissipation layer is obtained. 0.08 Al 0.92 A Pt-Ir-Rh high radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high conductivity and heat transfer layer. The Pt-Ir-Rh target was installed and fixed, and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of magnetron sputtering were as follows: vacuum degree 2.0 Pa, sputtering current 115 mA, sputtering time 30 min, correction factor 2.0, sample stage rotation speed 8 rpm, water inlet temperature 27 ° C, and return water temperature 61 ° C; the thickness of the Pt-Rh high radiation heat dissipation layer was 6 μm.

[0068] Example 6

[0069] The difference between this embodiment and embodiment 1 is that:

[0070] Vacuum atmospheric plasma spraying on C fWhen preparing the Si-Al2O3 bonding layer on the ZrC substrate, vacuum atmospheric plasma spraying parameters were: power supply 62.7 kW, operating current 570 A, operating voltage 110 V, argon flow rate 2150 L / h, hydrogen flow rate 680 L / h, powder feed rate 270 L / h, rotation speed 1.0 r / s, and cooling temperature 60°C. The Si-based bonding layer achieved a coating thickness of 70 μm and a density of 99%.

[0071] BN-RE x Al 1-x The RE of the TaO4 high-conductivity heat transfer layer is Lu, and BN-Lu is obtained. 0.04 Al 0.96 TaO4 ceramic high conductivity heat transfer layer is prepared by supersonic flame spraying on the surface of Si-Al2O3 bonding layer. 0.04 Al 0.96 When spraying TaO4 ceramic high-conductivity heat transfer layer, the supersonic flame spraying parameters are set as follows: barrel length 4 inches, oxygen flow rate 2040SCFH, kerosene flow rate 7.3gpm, powder feed rate 65g / min, carrier gas flow rate 20SCFH, spray distance 350mm, step distance 4mm, and linear speed 370mm / s. 0.04 Al 0.96 The coating thickness of the TaO4 ceramic high-conductivity heat transfer layer is 121 μm and the density is 93%.

[0072] The A in the Pt-A ​​metal high radiation heat dissipation layer is Mo-Co, and a Pt-Mo-Co high radiation heat dissipation layer is obtained. 0.04 Al 0.96 A Pt-Mo-Co high-radiation heat dissipation layer was prepared on the surface of the TaO4 ceramic high-conductivity heat transfer layer. The Pt-Mo-Co target was installed and fixed, and the thermal sprayed sample was placed horizontally on a rotating stage with the coating facing the target. The specific settings of magnetron sputtering were as follows: vacuum degree 1.9 Pa, sputtering current 105 mA, sputtering time 20 min, correction factor 1.0, sample stage rotation speed 8 rpm, water inlet temperature 27 ° C, and return water temperature 63 ° C; the thickness of the Pt-Rh high-radiation heat dissipation layer was 8 μm.

[0073] The process parameters of the silicon-based bonding layer in Examples 1-6 are shown in Table 1.

[0074] Table 1

[0075] parameter Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Power supply power (kw) 40 46.2 53.4 51.9 59.2 62.7 Working current (A) 500 550 600 570 580 570 Operating voltage (V) 80 84 89 91 102 110 Argon flow rate (L / h) 2000 2100 2300 2600 2400 2150 Hydrogen flow rate (l / h) 500 530 550 650 520 680 Powder feeding rate (L / h) 200 210 300 350 250 270 Speed ​​(r / s) 0.7 0.9 0.8 1.2 1.4 1.0 Cooling temperature (℃) 50 50 50 64 60 60 Thickness (μm) 50 59 65 80 74 70 Density (%) 96 98 98 96 97 99

[0076] The process parameters of the high-conductivity heat transfer layer in Examples 1-6 are shown in Table 2.

[0077] Table 2

[0078] parameter Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[Coated BN-RE x Al 1-x TaO4(RE, x)]]> Y、0.02 Yb, 0.06 Sm, 0.04 Eu, 0.1 Ho, 0.08 Lu, 0.04 Oxygen flow rate (SCFH) 1600 1750 1730 1854 2100 2040 Kerosene flow rate (gpm) 6.0 7.5 7.0 7.8 8.5 7.3 Powder feeding rate (g / min) 40 51 57 42 59 65 Carrier gas flow rate (SCFH) 20 23 25 21 24 20 Spray distance (mm) 320 330 320 380 400 350 Step distance (mm) 4 6 7 5 6 4 Linear speed (mm / s) 300 400 450 410 350 370 Thickness (μm) 100 134 150 147 110 121 Density (%) 90 91 95 94 95 93

[0079] The process parameters of the high-radiative heat dissipation layer in Examples 1-6 are shown in Table 3.

[0080] Table 3

[0081] parameter Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Coating Pt-A(A) Ir Rh Mo Co Ir-Rh Mo-Co Vacuum degree (Pa) 1.3 1.3 1.7 1.5 2.0 1.9 Sputtering current (mA) 100 100 100 120 115 105 Sputtering time (min) 20 23 40 37 30 20 Correction Factor 1.0 1.5 1.5 1.0 2.0 1.0 Sample stage rotation speed (rpm) 6 6 6 10 8 8 Inlet water temperature (℃) 20 27 30 35 27 27 Return water temperature (℃) 50 60 68 70 61 63 Thickness (μm) 5 9 8 10 6 8

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that only the silicon-based adhesive layer and the high-conductivity heat transfer layer in the coating structure are prepared, and the radiation heat dissipation layer is not prepared.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that only the silicon-based adhesive layer and the radiation heat dissipation layer in the coating structure are prepared, and the high-conductivity heat transfer layer is not prepared.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 2 is that the high-conductivity heat transfer layer coating material is the common high-temperature protective material 8YSZ, and the other functional layer materials remain unchanged.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 2 is that the coating material of the radiation heat dissipation layer is prepared by sputtering a refractory metal that does not contain platinum black, and the materials of other functional layers remain unchanged.

[0090] The protective coating material obtained is as follows Figure 1 (right) shown.

[0091] Depend on Figure 1 It can be seen that due to the different content of the components in the outermost layer, different surface colors and morphologies are presented.

[0092] Comparative Example 5

[0093] The difference between this comparative example and Example 2 is that the silicon-based bonding layer is prepared by ordinary atmospheric plasma spraying, and the preparation methods of other functional layers remain unchanged.

[0094] Comparative Example 6

[0095] The difference between this comparative example and Example 3 is that the thickness of each functional ceramic layer is increased by 75 μm, the total thickness of the coating system is increased by 150 μm, and other preparation processes remain unchanged.

[0096] Experimental Example 1 Performance Testing

[0097] (1) The coating system samples obtained in Comparative Examples 1 and 2 were subjected to low-temperature testing of the surface emissivity of the coating system samples using a light source adjustment reflection measurement method.

[0098] The specific steps are as follows: before placing the sample, place a calibrated high-reflection plane mirror so that the sample surface is oriented consistently with the axial interface of the semi-paraboloid, and the measurement area on the sample surface covers the focus of the semi-paraboloid reflector. Adjust the heating device to set the set temperature, and then measure the 360° spherical space reflection and scattering intensity by adjusting the orientation of the heating device. Calculate the emissivity of the material surface by calculating the reflectivity of the material surface in the entire space.

[0099] like Figure 3 As shown, Figures a and b represent the emissivity measured at 0.5-1.1 μm for the surfaces of the samples obtained in Examples 1 and 2 of the present invention. The extremely high emissivity of 0.88-0.98 is due to the coupling effect of the surface platinum black coating material and the surface roughness, significantly improving the heat dissipation capacity of the protective coating in service environments. In contrast, the surface emissivities of the coatings in Comparative Examples 1 and 4, represented by curves c and d, only reach 0.47-0.55 and 0.13-1.18, respectively, which are difficult to meet the application requirements of protective coatings on the surface of high-conductivity carbon fiber reinforced composite materials. This demonstrates the superiority of the surface radiative heat dissipation layer and its coating material selection in the preparation process of the present invention.

[0100] (2) The thermal conductivity of the samples prepared in Example 1, Example 6, Comparative Example 2, and Comparative Example 3 was measured.

[0101] like Figure 4 As shown, Figures a and b show the temperature dependence curves of the thermal conductivity of the coating systems of Examples 1 and 6, respectively. From room temperature to 900°C, they can reach above 6.4 W·K-1·m-1. This allows the heat absorbed by the high-emissivity layer to be quickly transferred to the composite substrate, and the redundant heat is dissipated to other areas of the component along the high-conductivity fibers, thereby reducing regional stress concentration and significantly improving the service life of the composite material. Figures c and d show the thermal conductivity of the coating systems of Comparative Examples 2 and 3, respectively. As can be seen from the figures, at 900°C, they can only reach 3.3 W·K-1·m-1 and 1.25, respectively, which do not meet the coating performance requirements. Therefore, the coating system obtained by the preparation process of the present invention, the selection of the high-conductivity heat transfer layer and its coating material will affect the thermal conductivity and surface emissivity of the coating system.

[0102] (3) The protective coatings obtained in Examples 1-6 and Comparative Examples 1-6 were placed in a high-temperature muffle furnace and heated to 1400° C., and then quenched to room temperature by cooling gas. The number of thermal cycles at which microcracks appeared in the coatings was recorded. The results are shown in Table 4:

[0103] Table 4

[0104] Sample Thermal cycle times Sample Thermal cycle times Example 1 56 Comparative Example 1 20 Example 2 60 Comparative Example 2 12 Example 3 54 Comparative Example 3 14 Example 4 78 Comparative Example 4 23 Example 5 56 Comparative Example 5 7 Example 6 70 Comparative Example 6 10

[0105] As can be seen in Table 4, the high-thermal conductivity and high-emissivity protective coating prepared by the coating preparation method of the present invention exhibits extremely high thermal cycling resistance. This is due to the excellent high-temperature stability of the functional layer materials and their high thermal compatibility with the substrate. Furthermore, the high heat dissipation and high thermal conductivity reduce stress concentration and improve the coating's resistance to crack propagation. In contrast, the silicon-based bonding layer prepared by conventional atmospheric plasma spraying in the coating structure of Comparative Example 5 exhibits a large amount of oxygen during the preparation process, leading to the formation of thermally grown oxides between the lamellar structures. This reduces the bonding layer's fracture toughness and bonding strength, making it difficult to achieve long-term stability in the coating structure during high-temperature thermal cycling tests. In Comparative Example 6, due to the significant increase in the overall coating system thickness, stress rapidly concentrates within the coating, reducing the stability of weak areas at the tip and edge of the component, resulting in rapid crack growth in the coating during high-temperature thermal cycling tests.

[0106] In summary, the protective coating prepared by the present invention has excellent bonding strength, phase structure stability and chemical compatibility. Compared with ordinary high-temperature protective coatings, this coating has higher thermal conductivity and emissivity. During high-temperature service, it can quickly transfer heat from the tip hotspot area to the high-conductivity fiber to release the accumulated stress. The higher emissivity further transfers the redundant heat on the coating surface to the service environment in the form of electromagnetic waves, greatly increasing the operating temperature of the composite material in an oxidizing environment and extending the service life of the leading edge components of the aircraft.

[0107] The above detailed description of the specific embodiments of the invention is intended to be illustrative only, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of the present invention. Therefore, equivalent changes, modifications, and improvements made without departing from the spirit and scope of the present invention are also encompassed within the scope of the present invention.

Claims

1. A high thermal conductivity and high emissivity protective coating, characterized by: The invention comprises a carbon fiber reinforced ceramic matrix composite material matrix, on which a silicon-based bonding layer, a high heat conduction layer and a high radiation heat dissipation layer are sequentially prepared to form a high thermal conductivity and high emissivity protective coating; The silicon-based bonding layer is composed of dispersed Al2O3 doped phase optimized Si ceramic material; the high conductivity heat transfer layer is composed of BN-RE x Al 1-x The high-radiation heat dissipation layer is composed of TaO4 ceramic material, the RE is one of Y, Yb, Sm, Eu, Ho or Lu, and the value of x is in the range of 0.02-0.1; the high-radiation heat dissipation layer is composed of Pt-A ​​metal, A is one or two of Ir, Rh, Mo or Co, and the one or two of Ir, Rh, Mo or Co are optimized platinum black layers to constitute the high-radiation heat dissipation layer.

2. The high thermal conductivity and high emissivity protective coating according to claim 1, characterized in that: The thickness of the silicon-based bonding layer is 50-80 μm, the thickness of the high-conductivity heat transfer layer is 100-150 μm, the thickness of the high-emissivity heat dissipation layer is 5-10 μm, and the total thickness of the high-thermal-conductivity and high-emissivity protective coating system is 155-240 μm.

3. The high thermal conductivity and high emissivity protective coating according to claim 1, wherein: The density of the silicon-based bonding layer is 96-99%; the density of the high-conductivity and heat-transfer layer is 90-95%.

4. A method for preparing a high thermal conductivity and high emissivity protective coating according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Screening the spray powders of the silicon-based bonding layer and the high-conductivity heat transfer layer respectively to obtain the silicon-based bonding layer spray spherical powder and the high-conductivity heat transfer layer spray spherical powder with uniform fluidity and particle size distribution, and setting aside for use; (2) Pretreating the carbon fiber reinforced ceramic matrix composite matrix to obtain a carbon fiber reinforced ceramic matrix composite matrix with a rough and clean surface; (3) Using vacuum plasma spraying to prepare a silicon-based bonding layer on the surface of a rough and clean carbon fiber reinforced ceramic matrix composite matrix; (4) Using supersonic flame spraying to prepare a high-conductivity heat transfer layer on the surface of the silicon-based bonding layer to obtain a spray coating system; (5) heat-treating the spray coating system using a muffle furnace until the stress inside the spray coating system is removed, thereby obtaining a stress-removed spray coating; (6) Magnetron sputtering is used to prepare a high-radiation heat dissipation layer on the surface of the spray coating, that is, a high thermal conductivity and high emissivity protective coating on a carbon fiber reinforced ceramic matrix composite matrix is ​​obtained.

5. The method for preparing a high thermal conductivity and high emissivity protective coating according to claim 4, wherein: The fluidity of the spherical powder sprayed on the silicon-based bonding layer in step (1) is 25-40s / 50g, and the particle size distribution is 25-50μm; the fluidity of the powder sprayed on the high-conductivity and heat-transfer layer is 35-55s / 50g, and the particle size distribution is 37-80μm.

6. The method for preparing a high thermal conductivity and high emissivity protective coating according to claim 4, wherein: The pretreatment in step (2) is to use sandpaper with increasing mesh size of 80-320 to polish the carbon fiber reinforced ceramic matrix composite material matrix in sequence, rinse the surface grinding residue with anhydrous ethanol, and then place it in a high temperature drying at 80-110°C for 30-90 minutes. After drying, the carbon fiber reinforced ceramic matrix composite material matrix is ​​sandblasted with 1-40 mesh gravel, and purged after the sandblasting is completed to obtain a carbon fiber reinforced ceramic matrix composite material matrix with a rough and clean surface.

7. The method for preparing a high thermal conductivity and high emissivity protective coating according to claim 4, wherein: The parameters of the vacuum plasma spraying method in step (3) are: power supply power 40-66kW, operating current 500-600A, operating voltage 80-110V, argon flow rate 2000-2700L / h, hydrogen flow rate 500-700L / h, four-way powder feeding rate of 200-350L / h, rotation speed 0.7-1.5r / s, and cooling temperature 50-70°C.

8. The method for preparing a high thermal conductivity and high emissivity protective coating according to claim 4, wherein: The parameters of the supersonic flame spraying method in step (4) are as follows: oxygen flow rate 1600-2100 SCFH, kerosene flow rate 6-8.5 gpm, powder feeding rate 40-65 g / min, carrier gas flow rate 20-25 SCFH, spray distance 320-400 mm, step distance 4-7 mm, and linear speed 300-450 mm / s.

9. The method for preparing a high thermal conductivity and high emissivity protective coating according to claim 4, wherein: The heat treatment parameters in step (5) are heat treatment at 900-1150°C for 1.5-3h; the magnetron sputtering parameters in step (6) are vacuum degree 1.3-2.0Pa, sputtering current 100-120mA, sputtering time 20-40min, correction factor 1.0-2.0, sample stage rotation speed 6-15rpm, water inlet temperature 20-35°C, and return water temperature 50-70°C.

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